Rotating devices such as turntables are used in a variety of applications to turn heavy equipment, vehicles, machinery, buildings, seating or other items that are difficult to turn due to weight, space constraints or directional constraints. For example, a rail car engine can be turned on a turntable to quickly re-orient the engine or switch tracks in a rail yard. Turntables may also be used in revolving restaurants, dance floors, stadium seating, auditoriums, homes and other applications where large items need to be rotated or positioned. Rotating devices are often built for the custom needs of each application, whether it be a turntable for positioning manufacturing equipment in a factory or a turntable for positioning rail cars, buildings or other machinery, each application may have different requirements such as size, height and load bearing capacity.
U.S. Pat. No. 7,631,602 to Schwenker discloses a low profile turntable device having concentric circular and perpendicular lateral band systems for mounting the turntable on a surface. The concentric and perpendicular lateral bands are joined with a clip. The concentric and perpendicular lateral bands generally lie in the same plane and are joined to create a generally two dimensional structure of sheet metal parts.
U.S. Pat. No. 6,877,437 to Murdock discloses a modular, flexible turntable that is designed to be mounted to an uneven surface. A series of petals extend outwards and are attached to a central disk. The attachment point between the petals and the disc is flexible, and the petals and disc may be fastened together using welding.
Other versions of turntables are assembled from a series of I-Beam structures that are cut and fit to create a rounded support structure. An example of a prior art turntable is shown in FIGS. 5A and 5B, and described in detail below. The support structure of the turntable is designed to support the load of the item to be placed on the turntable. Often, the item is heavy and requires a substantial support structure. For example, the item may be a rail car engine.
The I-Beams and flat metal parts are cut and fit so that the parts can be joined. Often, tolerances associated in forming I-Beams are not acceptable for producing machinery that is designed to move. On the other hand, custom formed I-Beams with tighter tolerances are a prohibitively expensive alternative. Since each part is aligned and welded individually, and the tolerances, straightness and flatness of the beams are not high enough, the fitting and cutting process is extremely labor intensive. The final structure may also have an outer ring formed from a rolled structural member affixed to the outside of the turntable. If the turntable is for rail cars, a track must also be affixed to the turntable, typically directly above the underlying I-Beams of the support structure.
Prior art turntables also require repeated measurements to check the center and alignment of the pieces of the turntable as the turntable is assembled. Often, these repeated measurements are done by a worker who specializes in welding. A turntable and method of manufacture thereof that make more efficient use of specialized labor is desired to increase efficiency in production.
There is a need for an improved turntable and manufacturing method thereof that overcomes the disadvantages of the prior art. It is desirable to manufacture a turntable using a method that achieves tolerance requirements with less time devoted to measuring, cutting and fitting. It is further desirable to construct a turntable using a method that requires reduced fitting and alignment skills from workers in order to assemble the turntable. It is further desirable to construct a turntable using a method that allows for reduced lead times during manufacturing.